Objective:To investigate the effects of the abnormal expression of myo-inositol oxygenase (MIOX) on the expression of TGF-β1 in rat renal tubular epithelial cells under high glucose. Methods:① In vitro, rat renal tubular epithelial cell line NRK-52E was maintained in dulbecco’s modified eagle’s medium (DMEM) containing 5.6 mmol/L glucose and 10% fetal bovine serum (FBS). Then the cells were treated with D-glucose at different concentrations (ranging from 15 to 30 mmol/L) for 48 h, D-mannitol served as control. Gene expressions were analyzed at mRNA level by semi-quantitative RT-PCR and at protein level by Western blot. ② The expressions of MIOX mRNA and protein were observed in NRK-52E cells treated with TGF-β1 at different concentrations (ranging from 1 to 25 mmol/L) for 48 h. ③ Transient transfection of the normal NRK-52E cells with anti-sense oligodeoxynucleotide (ASODN) for 8 h was performed to knockdown MIOX gene using LipofectamineTM 2000. The cells were then treated with D-glucose at concentration of 30 mmol/L for 48 h. Gene expressions were analyzed at mRNA level by RT-PCR and at protein level by Western blot. Results:① In vitro, the expression of MIOX mRNA and protein in NRK-52E cells was induced by high D-glucose in a dose-dependent manner. Paralleled increases were observed with respect to TGF-β1 (P < 0.05). ② There was no significant difference of the MIOX mRNA and protein levels in NRK-52E cells between each group after the stimulation of TGF-β1 at different concentrations (ranging from 1 to 25 mmol/L,P > 0.05). ③ Transient transfection of the normal NRK-52E cells with ASODN significantly attenuated the increase of TGF-β1 expression in normal NRK-52E cells induced by high D-glucose (P < 0.05). Conclusion:High glucose can induce the expression of MIOX and TGF-β1 gene in NRK-52E cells in a dose-dependent manner. MIOX might play a role in the progression of diabetic nephropathy in rat renal tubular epithelial cells through the activation of cytokine TGF-β1.